How to repair the broken sound button of square dance?

The situation is still unclear. If it is a "button", it may be that the optical wiring for digitally controlling the volume is not good. We have to change the button.

If it is that kind of "knob". Then consider removing the direct connection directly: the result is the maximum volume output.

It is recommended to go to the electrical repair shop to see the situation, which is only a dozen dollars.